DRAM and SDRAM Memory Chips Information

Dynamic random access memory (DRAM) chips are single-transistor memory cells that use small capacitors to store each bit of memory in an addressable format that consists of rows and columns. Because capacitors are unable to hold a charge indefinitely, DRAM memory chips require a near-constant pulse of current to retain stored information. If DRAM memory chips are not refreshed, data is lost. Though less expensive than synchronous random access memory (SRAM), DRAM requires extra processing time to restore the contents of memory addresses. DRAM is used widely in personal computers and workstations. Common DRAM types include extended fast page mode (FPM) DRAM and extended operation (EO) DRAM.

Selection Criteria

Selecting DRAM memory chips requires an analysis of performance specifications such as access time, refresh rate, and refresh options.

Measured in nanoseconds (ns), access time indicates the speed of memory and represents a cycle that begins when the CPU sends a request to memory and ends when the CPU receives the data requested.

The refresh rate, which is typically expressed in kilobytes (KB), describes the size of the data that must be recharged.

Self-refreshing DRAM memory chips include technology that refreshes the device independently of the CPU or external refresh circuitry. Self-refreshing DRAM memory chips reduce power consumption dramatically and are commonly used in notebook and laptop computers.

First-in, first-out (FIFO) memory chips are used in buffering applications between devices that operate at different speeds or in applications where data must be stored temporarily for further processing.

Memory chips are internal storage areas in computers. Although the term "memory chip" commonly refers to a computer's random access memory (RAM), this product area includes many different types of electronic data storage. Computer memory stores data electronically in cells. Without memory chips, a computer could not read programs or retain data.